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Steel-Concrete Composite Floor Systems Subject to Fire – Phase 2

Compartment fire test of a two-story steel gravity frame with composite floors.
Compartment fire test of a two-story steel gravity frame with composite floors.
Credit: NIST

This study experimentally investigates the fire-structure interaction and failure mechanisms of steel-concrete composite floor systems commonly used in steel-framed buildings. The full-scale two-story steel gravity frame two bays by three bays in plan are used to mimic the realistic boundary conditions of the 6.1 m x 9.1 m composite floor specimens including beam-end connections and slab continuity to the adjacent bays. To simulate imposed gravity loads during fire in accordance with the current American Society of Civil Engineers (ASCE) 7 standard, the composite floor specimen is hydraulically loaded to 2.7 kPa, and the surrounding (cool) floors were loaded to 1.2 kPa using water-filled drums. The fire test compartment (10 m x 6.9 m x 3.8 m) and four 1 m x 1.5 m natural gas burners (rated 16 MW total) are used to create realistic fire exposure to the composite floor specimen soffit. Over 300 data channels are deployed to measure applied fire and mechanical loading as well as thermal and structural responses at various locations in the two-story building during and after fire exposure.

A total of three compartment fire experiments were conducted to investigate the fire resilience of composite floor systems with a variety of influencing factors including the amount of steel reinforcement in the concrete slab and the passive fire protection scheme for the steel frame in the fire test bay, and the structural loading.

The menu provides access to the completed experiments including the full test report, videos, and data.



Created August 15, 2018, Updated January 4, 2024